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BACKGROUND-ORIENTED SCHLIEREN FOR FLOW AND THERMAL SYSTEMS: PRINCIPLES OF IMAGE FORMATION AND APPLICATIONS
Journal
Journal of Flow Visualization and Image Processing
ISSN
10653090
Date Issued
2022-01-01
Author(s)
Srivastava, Atul
Narayan, Surya
Kumar, Gulshan
Abstract
Imaging fluid flow and transport phenomena has gained considerable attention in the recent past. The imaging techniques are not only limited to visualization tools but, when coupled with suitable data reduction algorithms, can lead to the generation of the complete whole field quantitative data of flow and transported properties. In this direction, the technique of background-oriented schlieren (BOS) is one of the latest developments that has garnered significant attention among the research community. The present article reviews the plausible configurations of the BOS system, including principles of image formation and its applications in the domain of flow and thermal systems. Particular attention is paid to various constraints that one faces while configuring the imaging technique correctly from its first principles and those associ-ated with the development of data reduction methodologies for BOS image analysis. Various modifications affected in the standard BOS, since the time it was proposed by Meier et al. (2002, 2013), for mapping the flow and transported properties as well as thickness variations of liquid surfaces are reviewed. Following an extensive review of the available literature, the potential of BOS in imaging single-as well as two-phase heat transfer phenomena is demonstrated by setting up lab-based test configurations that include natural convection over a heated vertical flat plate and horizontally placed circular cylinder, and the evaporation dynamics of impinging acetone droplet(s). The recorded BOS images are quantitatively analyzed to re-trieve the field distribution of parameters of interest in each of the configurations studied.
Volume
29
Subjects